METAL COMPLEXES
20230271989 · 2023-08-31
Inventors
- Anna Hayer (Darmstadt, DE)
- Rouven Linge (Darmstadt, DE)
- Armin Auch (Darmstadt, DE)
- Philipp STOESSEL (Darmstadt, DE)
- Nils Koenen (Darmstadt, DE)
Cpc classification
C09K2211/1044
CHEMISTRY; METALLURGY
C09K2211/1029
CHEMISTRY; METALLURGY
International classification
C07F15/00
CHEMISTRY; METALLURGY
Abstract
The present invention relates to dinuclear metal complexes and to electronic devices, especially organic electroluminescent devices, comprising these metal complexes.
Claims
1.-15. (canceled)
16. A compound of formula (1) ##STR00405## where the symbols and indices used are as follows: X is the same or different at each instance and is a group of the formula —(Ar).sub.n—R; Y is the same or different at each instance and is R or X; Z is the same or different and is R or X; Ar is the same or different at each instance and is a divalent group selected from the structures (Ar1) to (Ar7) ##STR00406## where the dotted bond represents the linkage of the units and V is CR.sub.2, O, S or NR; n is the same or different at each instance and is an integer from 3 to 20, with the proviso that, in each —(Ar).sub.n—R unit, at least 5 phenyl and/or cyclohexyl groups are joined to one another in a linear manner; R may occur once or more than once and is the same or different at each instance and is H, D, F, Cl, Br, I, N(R.sup.1).sub.2, CN, NO.sub.2, OR′, SR′, COOH, C(═O)N(R.sup.1).sub.2, Si(R.sup.1).sub.3, B(OR.sup.1).sub.2, C(═O)R′, P(═O)(R.sup.1).sub.2, S(═O)R.sup.1, S(═O).sub.2R.sup.1, OSOR.sup.1, a straight-chain alkyl group having 1 to 20 carbon atoms or an alkenyl or alkynyl group having 2 to 20 carbon atoms or a branched or cyclic alkyl group having 3 to 20 carbon atoms, where the alkyl, alkenyl or alkynyl group may in each case be substituted by one or more R.sup.1 radicals, where one or more nonadjacent CH.sub.2 groups may be replaced by Si(R.sup.1).sub.2, C═O, NR.sup.1, O, S or CONR.sup.1, or an aromatic or heteroaromatic ring system which has 5 to 40 aromatic ring atoms and may be substituted in each case by one or more R.sup.1 radicals; at the same time, two R radicals together may also form a ring system; R.sup.1 is the same or different at each instance and is H, D, F, Cl, Br, I, N(R.sup.2).sub.2, CN, NO.sub.2, OR.sup.2, SR.sup.2, Si(R.sup.2).sub.3, B(OR.sup.2).sub.2, C(═O)R.sup.2, P(═O)(R.sup.2).sub.2, S(═O)R.sup.2, S(═O).sub.2R.sup.2, OSOR.sup.2, a straight-chain alkyl group having 1 to 20 carbon atoms or an alkenyl or alkynyl group having 2 to 20 carbon atoms or a branched or cyclic alkyl group having 3 to 20 carbon atoms, where the alkyl, alkenyl or alkynyl group may in each case be substituted by one or more R.sup.2 radicals, where one or more nonadjacent CH.sub.2 groups may be replaced by Si(R.sup.2).sub.2, C═O, NR.sup.2, O, S or CONR.sup.2, or an aromatic or heteroaromatic ring system which has 5 to 40 aromatic ring atoms and may be substituted in each case by one or more R.sup.2 radicals; at the same time, two or more R.sup.1 radicals together may form a ring system; R.sup.2 is the same or different at each instance and is H, D, F or an aliphatic, aromatic or heteroaromatic organic radical, especially a hydrocarbyl radical, having 1 to 20 carbon atoms, in which one or more hydrogen atoms may also be replaced by F.
17. The compound according to claim 16 of formula (1a) ##STR00407## where the symbols have the definitions given in claim 16.
18. The compound according to claim 16, wherein the two substituents X are the same.
19. The compound according to claim 16, selected from the structures of the formulae (1a-1), (1a-2) and (1a-3) ##STR00408## where the two groups X chosen are the same, and where the Y groups in formula (1a-2) are each a —(Ar).sub.n—R group and are the same, and where the Z group in formula (1a-3) is a —(Ar).sub.n—R group.
20. The compound according to claim 16, wherein the R radical in the —(Ar).sub.n—R group is the same or different at each instance and is H, a linear alkyl group having 1 to 10 carbon atoms or a branched or cyclic alkyl group having 3 to 10 carbon atoms.
21. The compound according to claim 16, wherein the structures (Ar1) are selected from the structures (Ar1a) to (Ar1f) ##STR00409## where the dotted bonds represent the linkage of the structures, W is C(R.sup.1).sub.2, O, S or NR.sup.1, and R and R.sup.1 have the definitions given in claim 16; and in that the structures (Ar2) are selected from the structures (Ar2a) and (Ar2b), ##STR00410## where the dotted bonds represent the linkage of the structures, and R and V have the definitions given in claim 16; and in that the structures (Ar3) are selected from the structures (Ar3a), ##STR00411## where the dotted bonds represent the linkage of the structure; and in that the structures (Ar4) are selected from the structures (Ar4a) and (Ar4b), ##STR00412## where the dotted bonds represent the linkage of the structure, and R has the definitions given in claim 16; and in that the structures (Ar5) are selected from the structures (Ar5a) and (Ar5b), ##STR00413## where the dotted bonds represent the linkage of the structure, and R has the definitions given in claim 16; and in that the structures (Ar7) are selected from the structures (Ar7a), ##STR00414## where the dotted bonds represent the linkage of the structure.
22. The compound according to claim 16, wherein at least one Ar group is the same or different at each instance and is selected from the structures (Ar1) and/or (Ar2).
23. The compound according to claim 16, wherein n is an integer from 5 to 20, wherein the groups (Ar1) to (Ar7) are chosen such that a total of 8 to 24 phenyl or cyclohexane groups are joined to one another in a linear manner.
24. The compound according to claim 16 of formula (2), ##STR00415## where the symbols used have the definitions listed in claim 16.
25. The compound according to claim 16, wherein all four phenylpyridine subligands have the same substitution.
26. A process for preparing the compound according to claim 16 comprising reacting a compound substituted by reactive leaving groups in place of X and optionally Y and/or Z with a compound A-(Ar).sub.n—R, where A is a reactive leaving group.
27. A formulation comprising at least one compound according to claim 16 and at least one further compound and/or at least one solvent.
28. A method comprising incorporating the compound according to claim 16 in an electronic device.
29. An electronic device comprising at least one compound according to claim 16.
30. The electronic device according to claim 29 which is an organic electroluminescent device, wherein the compound is used as an emitting compound in one or more emitting layers in combination with one or more matrix materials and/or in combination with one or more further triplet emitters.
Description
EXAMPLES
[0133] The syntheses which follow, unless stated otherwise, are conducted under a protective gas atmosphere in dried solvents. The metal complexes are additionally handled with exclusion of light or under yellow light. The solvents and reagents can be purchased, for example, from Sigma-ALDRICH or ABCR. The respective figures in square brackets or the numbers quoted for individual compounds relate to the CAS numbers of the compounds known from the literature.
[0134] Synthesis of the X Groups:
##STR00250##
[0135] Synthesis of B1
[0136] 26 g (33.7 mmol) of A1 (CAS 2171483-83-1) is dissolved in 600 ml of dichloromethane. Subsequently, 7.2 g (44 mmol) of N-bromosuccinimide is added in portions, one drop of HBr is added and the mixture is stirred at room temperature. After 48 h, 200 ml of aqueous sodium hydrogensulfite solution (30%) is added and the mixture is stirred for 1 h. Subsequently, the two phases are separated, and the organic phase is extracted with water and then concentrated under reduced pressure. The residue is admixed with 300 ml of n-heptane and refluxed for 1 h. After the mixture has been cooled, the colourless solids are filtered and dried under reduced pressure. Yield: 25.3 g (32 mmol), corresponding to 97% of theory.
[0137] The following compounds can be prepared analogously:
TABLE-US-00006 Reactant Product B2
[0138] Synthesis of C1:
[0139] To 28.0 g (35.5 mmol) of B1, 33.6 g (35.5 mmol) of CAS 2171483-74-0 and 9.8 g (71 mmol) of potassium carbonate are added 1100 ml of THE and 550 ml of water. Subsequently, 373 mg (1.4 mmol) of triphenylphosphine and 325 mg (0.4 mmol) of tri(dibenzylideneacetone)dipalladium are added and the mixture is refluxed for 16 h. Subsequently, water and toluene are added to the reaction mixture, and the phases are separated. The aqueous phase is extracted twice with toluene and the combined organic phases are extracted once with water. The organic phase is filtered through alumina and then concentrated under reduced pressure. The product is purified by repeated crystallization from toluene/n-heptane 1:10 and obtained in solid form.
[0140] Yield: 41.0 g (28.8 mmol); 81% of theory.
[0141] The following compounds can be prepared analogously:
TABLE-US-00007 Boronic ester Bromide Product C2 CAS 2171483- 74-0 B4
[0142] Synthesis of D1:
[0143] To 25.3 g (18.7 mmol) of C1, 8.6 g (33.7 mmol) of bis(pinacolato)diboron, 5.5 g (56 mmol) of potassium acetate and 830 mg (1.1 mmol) of trans-dichlorobis(tricyclohexylphosphine)palladium(II) are added 750 ml of dioxane, and the mixture is refluxed for 48 h. Subsequently, toluene and water are added to the reaction mixture, and the phases are separated. The aqueous phase is extracted twice with toluene, and the combined organic phases are extracted twice with water, filtered through alumina and concentrated under reduced pressure. The residue is extracted by stirring with hot ethanol, and the product is obtained in solid form. Yield: 16.0 g (11.1 mmol), 60% of theory.
[0144] The following compounds can be prepared analogously:
TABLE-US-00008 Reactant D2 C2
[0145] Synthesis of E1:
[0146] To 5 g (6.4 mmol) of B1, 9.8 g (6.8 mmol) of D1 and 1.8 g (13 mmol) of potassium carbonate are added 800 ml of THE and 400 ml of water. Subsequently, 67 mg (0.26 mmol) of triphenylphosphine and 59 mg (0.06 mmol) of tri(dibenzylideneacetone)dipalladium are added and the mixture is refluxed for 16 h. Subsequently, water and toluene are added to the reaction mixture, and the phases are separated. The aqueous phase is extracted twice with toluene and the combined organic phases are extracted once with water. The organic phase is filtered through alumina and then concentrated under reduced pressure. The product is obtained in solid form by chromatography (SiO.sub.2, heptane/THF 1:20>1:10) and by repeated extraction by stirring from hot toluene.
[0147] Yield: 8.5 g (4.2 mmol), 66% of theory.
[0148] The following compounds can be prepared analogously:
TABLE-US-00009 Boronic E Reactant ester Product 2 B1 D2
[0149] Synthesis of Intermediate Int-1
##STR00312##
[0150] 3 g (13.2 mmol) of CAS 68797-61-5, 10.4 g (13.2 mmol) of D4, 3.7 g (27 mmol) of potassium carbonate and 0.76 g (0.66 mmol) of tetrakis(triphenylphosphine)palladium(0) are mixed in 500 ml of toluene/ethanol/water (2:1:1) and heated under reflux for 18 h. On completion of conversion, the reaction mixture is cooled down to room temperature. The organic phase is extended with toluene and washed twice with water and once with saturated aqueous sodium chloride solution. The organic phases are combined and concentrated on a rotary evaporator. The product is purified by column chromatography (SiO.sub.2; THE/heptane). Yield: 4.3 g (5.3 mmol; 40%).
[0151] Synthesis of Intermediate Int-2
##STR00313##
[0152] 15.0 g (100.7 mmol) of 4,6-dichloropyrimidine, 38.5 g of (4-chloro-3-methoxyphenyl)boronic acid, 55.7 g (402.7 mmol) of potassium carbonate and 2.8 g (4.0 mmol) of bis(triphenylphosphine)Pd(II) chloride are dissolved in 300 ml of acetonitrile/ethanol (2:1) and heated under reflux for 16 h. On completion of conversion, the reaction mixture is left to cool down to room temperature. The precipitated solids are filtered off with suction and washed with toluene and methanol. The filtrate is concentrated on a rotary evaporator. The solids obtained are purified by crystallization from dichloromethane/methanol. Yield: 20.9 g (57.9 mmol; 58%)
[0153] The following compound can be prepared analogously from the
TABLE-US-00010 Boronic acid Reactant Product Int-2b CAS 1679-18-1 Int-1
[0154] Synthesis of Intermediate Int-3
##STR00315##
[0155] 16.0 g (44.3 mmol) of Int-2, 24.3 g (95.7 mmol) of bis(pinacolato)diborane and 17.4 g (177.2 mmol) of potassium acetate are dissolved in 1000 ml of THF. After addition of 1.87 g (2.2 mmol) of Xphos Pd G3, the reaction mixture is heated under reflux for 48 h. Subsequently, the reaction mixture is cooled down to room temperature and the solids are filtered off. The filtrate is concentrated on a rotary evaporator and purified by column chromatography (SiO.sub.2, heptane/ethyl acetate), and the product is isolated.
[0156] Yield: 12.4 g (22.7 mmol; 51%).
[0157] The following compound can be prepared analogously from the corresponding boronic ester:
TABLE-US-00011 Chloride Product Int-3b Int-2b
[0158] Synthesis of the Emitter Base Structure Stage 1
##STR00317##
[0159] An initial charge of 39.2 g (81 mmol) of EC1 (2202712-51-2), 54.0 g (170 mmol) of 2-bromo-4-chloro-1-iodobenzene, 44.8 g (324 mmol) of potassium carbonate and 570 mg (0.81 mmol) of bis(triphenylphosphine)palladium(II) chloride in 600 ml of toluene is stirred at 80° C. After 16 h, 300 ml of water is added. The phases are separated and the aqueous phase is extracted repeatedly with toluene, and the organic phase is washed repeatedly with water. The organic phases are combined and concentrated under reduced pressure. The resultant residue is stirred repeatedly with hot ethanol. The resultant solids are subjected to hot extraction with toluene over alumina. The precipitated solids are filtered. Yield: 35.1 g (57.5 mmol); 71% of theory.
[0160] The following compounds can be prepared analogously from the corresponding boronic esters:
TABLE-US-00012 Boronic ester Product EC2b Int-3
[0161] Synthesis of the Emitter Base Structure Stage 2
##STR00320##
[0162] 34.6 g (57 mmol) of EC2, 78.8 g (118 mmol) of 1989597-72-9 and 24 g (226 mmol) of sodium carbonate are suspended in 1.2 l of THE/water (2:1). After addition of 400 mg (0.57 mmol) of Pd(amphos)Cl.sub.2, the reaction mixture is refluxed for 16 h. The solids that precipitate out on cooling to room temperature are filtered and purified by means of repeated hot extraction over alumina (with dichloromethane as eluent) and subsequent crystallization from dichloromethane/methanol. Yield: 52.3 g (34.4 mmol), 61% of theory.
[0163] The following compounds can be prepared analogously from the corresponding boronic esters:
TABLE-US-00013 Boronic ester Product EC3b 2245948-53-0
[0164] Synthesis of the Emitter Core Stage 2-Int
##STR00328##
[0165] 28.2 g (18.1 mmol) of EC3g is dissolved in 250 ml of dichloromethane. After addition of 9 ml of pyridine, the mixture is cooled to 0° C., and 12 ml (73 mmol) of trifluoromethanesulfonic anhydride is added dropwise such that the temperature does not exceed 2° C. The mixture is stirred at this temperature for a further hour and then stirred at room temperature for 16 h. Subsequently, the reaction mixture is poured onto 600 ml of ice and stirred for 30 minutes. The mixture is transferred to a separating funnel, and the organic phase is extended with dichloromethane and washed three times with water. The combined aqueous phases are extracted twice with dichloromethane. The combined organic phases are filtered through silica gel and washed through with ethyl acetate. After the solvent had been removed on a rotary evaporator, the residue is extracted repeatedly by stirring with ethyl acetate at 60° C. After cooling to room temperature, the solids are filtered off and the product is obtained. Yield 28.1 g (15.4 mmol; 85%).
[0166] The following compound can be prepared analogously from the corresponding boronic ester:
TABLE-US-00014 Reactant Product EC3f- Int EC3f
[0167] Synthesis of EC3i
##STR00330##
[0168] 15.5 g (8.5 mmol) of EC3g-Int, 6.4 g (34.1 mmol) of 4-tert-butylphenylboronic acid, 4.7 g (34.1 mmol) of potassium carbonate, 0.73 g (1.7 mmol) of dppb and 0.39 g (0.43 mmol) of tris(dibenzylideneacetone)dipalladium(0) are dissolved in 1000 ml of dioxane/water (3:1), and stirred at 90° C. for 16 h. On completion of conversion, the organic phase is extended with ethyl acetate, and the phases are separated. The aqueous phase is extracted twice with ethyl acetate, and the combined organic phases are washed twice with water, dried over magnesium sulfate and filtered through silica gel. The desired product is obtained after purification by column chromatography (SiO.sub.2; toluene/ethyl acetate). Yield: 6.1 g (3.4 mmol; 40%).
[0169] The following compounds can be prepared analogously from the corresponding boronic esters:
TABLE-US-00015 Reactants Product EC3j Triflate: EC3g-Int Boronic ester: D1
[0170] Synthesis of the Emitter Base Structure Stage 3
##STR00333##
[0171] An initial charge of 52.3 g (34.4 mmol) of EC3, 35 g (71.5 mmol) of tris(acetylacetonato)iridium(III) and 523 g of hydroquinone is heated to 260° C. and stirred at that temperature for 2 h. Subsequently, the reaction mixture is allowed to cool, with dropwise addition of 500 ml of ethylene glycol at 220° C. and 2 l of methanol starting from 120° C. After cooling to room temperature, the precipitated solids are filtered through a double-ended frit. The diastereomeric metal complex mixture containing AA and AA isomers (racemic) and AA isomer (meso) in a molar ratio of 1:1 (determined by .sup.1H NMR) is dissolved in 300 ml of dichloromethane, applied to 100 g of silica gel and separated by chromatography with a silica gel column in the form of a toluene slurry, with maximum exclusion of light. The foremost spot, called isomer 1 (I1) hereinafter, is eluted first, followed by the later-eluting isomer, called isomer 2 (I2) hereinafter. And, after removing the solvents, a deep red solid is obtained. Yield: I1: 29 g (15.2 mmol), 45% of theory, I2: 24.3 g (12.7 mmol), 37% of theory.
[0172] The metal complexes shown below can in principle be purified by chromatography (typically using an automated column system (Torrent from Axel Semrau), recrystallization or hot extraction). Images of complexes adduced hereinafter typically show only one isomer. The isomer mixture can be separated, but can also be used in the OLED as an isomer mixture. However, there are also ligand systems in which only one pair of diastereomers forms for steric reasons.
[0173] The compounds which follow can be synthesized in an analogous manner. The chromatographic separation of the diastereomer mixture which is typically obtained is effected on flash silica gel in an automated column system (Torrent from Axel Semrau):
TABLE-US-00016 Reactant Product EC4b EC3b
[0174] Synthesis of the Emitter Base Structure Stage 4
##STR00342##
[0175] An initial charge of 11.7 g (6.2 mmol) of EC4, 3.3 g (13 mmol) of bis(pinacolato)diboron, 2.4 g (25 mmol) of potassium acetate and 453 mg (0.61 mmol) of trans-dichlorobis(tricyclohexylphosphine)palladium(II) in 600 ml of dioxane is refluxed for 16 h. After cooling to room temperature, 400 ml of water is added, followed by repeated extraction with dichloromethane, and the combined organic phases are extracted repeatedly with water. The organic phase is subsequently filtered through silica gel (dichloromethane) and concentrated under reduced pressure. The residue obtained is crystallized from dichloromethane/methanol. Yield 12.8 g (6.1 mmol), 98% of theory.
[0176] The following compounds can be prepared analogously:
TABLE-US-00017 Reactant Product EC5b EC4b
[0177] Synthesis of the Emitter Em1
##STR00351##
[0178] 2.7 g (1.3 mmol) of EC5, 5.3 g (2.6 mmol) of E1, 0.79 g (5.2 mmol) of caesium fluoride and 97 mg (0.13 mmol) of trans-dichlorobis(tricyclohexylphosphine)palladium(II) are dissolved in 80 ml of dioxane and refluxed for 16 h. After cooling to room temperature, dichloromethane and water are added to the reaction mixture, and the organic phase is removed. The aqueous phase is extracted twice with dichloromethane, and the combined organic phases are extracted with water and then concentrated under reduced pressure. The residue is repeatedly purified by chromatography (SiO.sub.2, heptane/dichloromethane) and then crystallized once again from dichloromethane/methanol. The resultant solids are dried under reduced pressure at 200° C. Yield: 2.7 g (0.47 mmol), 36% of theory.
[0179] The following compounds can be prepared analogously:
TABLE-US-00018 Reactant A Reactant B EC5b E1
Physics Examples
[0180] Production of the OLEDs and of the Films for the Photophysical Characterization
[0181] The complexes of the invention can be processed from solution. There are already many descriptions of the production of completely solution-based OLEDs in the literature, for example in WO 2004/037887 by means of spin coating. There have likewise been many previous descriptions of the production of vacuum-based OLEDs, including in WO 2004/058911. In the examples discussed hereinafter, layers applied in a solution-based and vacuum-based manner are combined within an OLED, and so the processing up to and including the emission layer is effected from solution and in the subsequent layers (hole blocker layer and electron transport layer) from vacuum. For this purpose, the previously described general methods are matched to the circumstances described here (layer thickness variation, materials) and combined as described hereinafter. The general structure is as follows: substrate/ITO (50 nm)/hole injection layer (HIL) (60 nm)/hole transport layer (HTL) (20 nm)/emission layer (EML) (60 nm)/hole blocker layer (HBL) (10 nm)/electron transport layer (ETL) (40 nm)/cathode (aluminium, 100 nm). The substrates used are glass plates coated with structured ITO (indium tin oxide) of thickness 50 nm. For better processing, they are coated with PEDOT:PSS (poly(3,4-ethylenedioxy-2,5-thiophene) polystyrenesulfonate, purchased from Heraeus Precious Metals GmbH & Co. KG, Germany). PEDOT:PSS is spun on from water under air and subsequently baked under air at 180° C. for 10 minutes in order to remove residual water. The hole transport layer and the emission layer are applied to these coated glass plates. The hole transport layer used is crosslinkable. A polymer of the structure depicted below is used, which can be synthesized according to WO 2013/156130:
##STR00396##
[0182] The hole transport polymer is dissolved in toluene. The typical solids content of such solutions is about 5 g/I when, as here, the layer thickness of 20 nm which is typical of a device is to be achieved by means of spin-coating. The layers are spun on in an inert gas atmosphere, argon in the present case, and baked at 220° C. for 30 minutes.
[0183] The emission layer is always composed of at least one matrix material (host material) and an emitting dopant (emitter). In addition, it is possible to use mixtures of a plurality of matrix materials and co-dopants. What is meant here by details given in such a form as TMM-A (92%):dopant (8%) is that the material TMM-A is present in the emission layer in a proportion by weight of 92% and dopant in a proportion by weight of 8%. The mixture for the emission layer is dissolved in toluene or optionally chlorobenzene. The typical solids content of such solutions is about 17 g/I when, as here, the layer thickness of 60 nm which is typical of a device is to be achieved by means of spin-coating. The layers are spun on in an inert gas atmosphere, argon in the present case, and baked at 160° C. for 10 minutes. The materials used in the present case are shown in table 1.
TABLE-US-00019 TABLE 1 EML materials used
[0184] The materials for the hole blocker layer and electron transport layer are applied by thermal vapour deposition in a vacuum chamber. The electron transport layer, for example, may consist of more than one material, the materials being added to one another by co-evaporation in a particular proportion by volume. Details given in such a form as ETM1:ETM2 (50%:50%) mean here that the ETM1 and ETM2 materials are present in the layer in a proportion by volume of 50% each. The materials used in the present case are shown in table 2. In the OLED components described here, ETM3 was used as HBL material, and ETM1:ETM2 (50:50) as ETL mixture.
TABLE-US-00020 TABLE 2 HBL and ETL materials used
[0185] The cathode is formed by the thermal evaporation of a 100 nm aluminium layer. The samples are encapsulated.
[0186] Films for photophysical characterization are produced as a single layer on quartz glass substrates by the process described above for emission layers. B1 is used here as host material, and 30 nm-thick films are produced. The samples are encapsulated.
[0187] Characterization:
[0188] Measurement of Emitter Orientation in the Solution-Processed Film
[0189] In the measurement setup, the solution-processed film containing the complex is irradiated with a laser, the molecules are excited and then the photoluminescence spectrum emitted is measured in an angle-dependent manner. The measured optical properties of the pure matrix material, using physical laws of optics, can be used to calculate a result for a potential 100% horizontal and 100% vertical orientation of the molecules. Subsequently, the measurements are fitted to the extreme orientations calculated and hence the orientation factor (optical orientation anisotropy) is determined. A perfect horizontal orientation of the molecules is described by Θ=0, the isotropic case by Θ=0.33, and the completely vertically aligned case by Θ=1. This value reflects the averaged orientation over all molecules in the layer that have been excited by the photoluminescence process, meaning that all complex molecules lie within the measurement spot irradiated by the laser. It is not possible to determine the orientation of a single molecule by this method. Frischeisen et al., Applied Physics Letters 96, 073302 (2010) and Schmidt et al., Phys. Rev. Appl. 8, 037001 (2017) describe the performance of such optical measurements for determination of emitter orientation.
[0190] Table 3 summarizes the optical orientation of the comparative material and the selected materials of the invention. The complexes of the invention are used in somewhat higher percentages by weight in order to compensate for the higher molecular weight. It is found that the two comparative complexes have an isotropic arrangement in the film, whereas complexes of the invention have more of a horizontal alignment.
TABLE-US-00021 TABLE 3 Optical orientation anisotropy ⊖ % in host Complex B1 ⊖ V1 D1 10 0.33 E1 Em1 15 0.26 V2 D2 10 0.33 E2 Em4 15 0.26 E3 Em5 15 0.26 E4 Em8 15 0.29 E5 Em16 15 0.27 E6 Em13 15 0.26 E7 Em12 15 0.28 E8 Em6 15 0.26 E9 Em11 15 0.28 E10 Em15 15 0.25 E11 Em10 15 0.28 E12 Em7 15 0.24 E13 Em14 15 0.27 E14 Em2 15 0.26 E15 Em3 15 0.26 E16 Em9 15 0.26 E17 Em17 15 0.27 E30 Em18 15 0.27 E31 Em19 15 0.28 E32 Em20 15 0.25 E33 Em21 15 0.26 E34 Em22 15 0.26
[0191] OLED Components:
[0192] The OLEDs are characterized in a standard manner. For this purpose, the electroluminescent spectra and the current-voltage-luminance characteristics (IUL characteristics) are determined assuming Lambertian radiation characteristics, and external quantum efficiency at a particular brightness is calculated as a performance figure.
[0193] All the components examined luminesce in the red. The EML mixtures used and results achieved are collated in table 4. The complexes of the invention are used in somewhat higher percentages by weight in order to compensate for the higher molecular weight. It is found that complexes of the invention with their more horizontal alignment achieve a distinct increase in quantum efficiency in the OLED component. More particularly, it is found that, in a direct comparison, for the same auxiliary ligand (D2 compared to Em4; D1 compared to Em1, Em13, Em12, Em7, Em14, Em9 and Em17), the substituents of the invention lead to an increase in quantum efficiency.
[0194] Any of the complexes of the invention adduced above can be used analogously and lead to comparable results.
TABLE-US-00022 TABLE 4 Results for solution-processed OLEDs (measured at a brightness of 1000 cd/m.sup.2) EQE Mixing ratio of Ex. Emitter [%] A1:B1:C1:emitter V3 D1 18.7 40:35:17:8 E18 Em1 26.1 40:33:17:10 V4 D2 21.8 40:35:17:8 E19 Em4 26.5 40:33:17:10 E20 Em5 26.2 40:33:17:10 E21 Em13 25.9 40:33:17:10 E22 Em12 23.2 40:33:17:10 E23 Em15 26.3 40:33:17:10 E24 Em7 26.5 40:33:17:10 E25 Em14 23.9 40:33:17:10 E26 Em2 25.7 40:33:17:10 E27 Em3 26.0 40:33:17:10 E28 Em9 26.0 40:33:17:10 E29 Em17 24.1 40:33:17:10 E35 Em18 24.2 40:33:17:10 E36 Em19 23.4 40:33:17:10 E37 Em20 26.4 40:33:17:10 E38 Em22 26.2 40:33:17:10